Waist was a common term in the United States for the bodice of a dress or for a blouse or woman's shirt from the early 19th century through the Edwardian period.
A shirtwaist was originally a separate blouse constructed like a shirt; i.e., of shirting fabric with turnover collar and cuffs and a front button closure. In the later Victorian period the term became applied more generally to unlined blouses with relatively simple construction and usually of a cotton or linen fabric, but often highly ornamented with embroidery and lace.
From the mid-20th century, shirtwaist referred to a dress with the upper portion (the bodice and sleeves) fashioned like a man's shirt, with a turnover collar and buttons down the front. Different embroidery were added to the shirtwaist, like rhinestones and different patterns.